In case of double twisting machines, there are endeavours to produce larger take-up bobbins which also have a correspondingly higher weight. These heavy take-up bobbins are difficult to handle, on account of which there are endeavours to transfer the take-up bobbins by means of a transfer device from the creel onto the conveyor belt running in the centre of the machine. In the case of an upward twisting machine of the kind mentioned hereinbefore (German Pat. No. 1 685 944), the actual creel which receives the take-up bobbin is pivotably connected to the end of the carrying arm. During winding, the creel can be locked in a given angular position relative to the carrying arm by a locking device. This locking device can be released when the bobbin is full, whereupon the carrying arm is pivoted towards the conveyor belt. The take-up bobbin in this case rolls over the take-up cylinder, or the movement of the creel can be controlled by a four-bar mechanism in such a way that the take-up bobbin is lifted above the take-up cylinder without contact. After opening the creel, the full take-up bobbin can drop onto the conveyor belt. In a development of this known upward twisting machine, the pivot axis of the carrying arm is arranged above the leading roller and the creel is located in the region between the leading roller and the take-up cylinder. Free access to the thread guiding parts is prevented not only by the carrying arm and the creel, but also by the take-up bobbin which increases in diameter during the winding process. Moreover, with this development the pivot radius of the bobbin axis of a take-up bobbin held in the creel is relatively small compared with the pivot axis of the carrying arm. From experience, however, this pivot radius should be as large as possible. In another embodiment of this known upward twisting machine, the pivot axis of the carrying arm is arranged at a greater height above the conveyor belt in the vertical longitudinal centre plane of the machine. As a result the overall height of the machine becomes relatively great and operation of the machine is made difficult. Moreover with this development it is difficult to provide a conveyor arranged above the machine for the supply of stock bobbins. Both embodiments furthermore have the disadvantage that the creel has to be pivotably connected to the carrying arm and there must also be at least one locking device. These additional structural components make the machine more expensive.
It is the object of the invention, while avoiding the above disadvantages, to provide an upward twisting machine, in particular double twisting machine, of the kind mentioned hereinbefore, in which free access to the thread guiding parts is ensured and in which no parts project beyond the take-up bobbin, so that it has a low overall height.
According to the invention this is achieved by the fact that the pivot axis of the carrying arm is provided in the region below the conveyor belt and that the pivot radius of the bobbin axis of a take-up bobbin held in the creel is dimensioned relative to the pivot axis in such a way that the line of contact between the bobbin winding and the take-up cylinder is always located on the side facing towards the vertical longitudinal centre plane, of a vertical plane passing through the axis of the take-up cylinder.
Due to the arrangement of the pivot axis of the carrying arm in the region below the conveyor belt, that is, at the centre of the machine, a particularly low overall height is obtained. No part of the carrying arm or of the creel projects beyond the take-up bobbin. Consequently a feeder for stock bobbins can without difficulty be arranged above the twisting machine at a level which is relatively low and hence also convenient to reach. As the carrying arm and the creel are arranged in the region between the take-up cylinder and the vertical longitudinal centre plane of the machine, free access to the thread-guiding parts from the operating side of the machine is ensured at any time.
A particularly advantageous development of the upward twisting machine consists in that the axis of the take-up cylinder is located above a horizontal plane of transport passing through the conveyor belt and that a cover plate sloping downwards towards the conveyor belt is provided as the transfer device between the take-up cylinder and the conveyor belt.
A similar construction is of course known from the aforementioned German Pat. No. 1 685 944. However, special advantages arise in combination with the characteristics of the upward twisting machine according to the invention. For the fact is that the creel can be rigidly connected to the carrying arm, whereby one joint and one locking device are saved. As the bobbin axis of the take-up bobbin in the device according to the invention is always located between a vertical plane passing through the axis of the take-up cylinder and the vertical longitudinal centre plane of the machine, the bobbin axis of the full take-up bobbin is located above the obliquely inclined cover plate. When the creel is opened, the take-up bobbin drops onto the cover plate and then rolls automatically onto the conveyor belt. Due to elimination of the pivot joint and the locking device, the production costs of the machine are lowered.
Further advantageous developments of the invention are discussed below.